This invention relates to a work piece transporting apparatus which may be employed, for example, in conjunction with a sheet metal forming press. In the usual operation of such a press, a work piece comprised of sheet metal is located at a forming station comprising a tool or die. The press is operated to form the sheet into the desired shape, and the formed work piece is then removed, and the next work piece located in position at the forming station.
Various attempts have been made to provide automatic means for transporting work pieces to the work station of a forming press or to work stations of other types of machinery. Such prior means include the apparatus disclosed in Ronbeck U.S. Pat. No. 3,902,606 issued on Sept. 2, 1975. In this apparatus, a gripping means for holding a sheet metal plate is attached at the lower end of a pivoting rod. The upper end of the rod carries a cam follower, and a cam path is defined adjacent this upper end whereby the gripping means can be moved along a path generally in the shape of an inverted U.
The path of movement as described in the foregoing patent permits use of the gripping means for picking up sheet metal pieces at a first station and then transporting of the pieces laterally to a position above the tool of a forming press. A vertical downward component of movement then serves to locate the work piece in position relative to the tool.
The gripping means of the patented structure is moved away during the forming operation and is then returned for picking up the work piece after forming, and for then laterally transporting the work piece away from the press.
In alternative arrangements utilizing systems of the type described in the aforementioned patent, a first gripping means may be employed for moving work pieces from a first station to the forming station. A second apparatus, located for example on the opposite side of the press, is them employed for picking up the formed piece and delivering the piece to a collection point. By utilizing separate machines for feeding and removing the work pieces, the forming operation can be carried out in a rapid and efficient manner.
All or portions of systems of the general type contemplated by this invention are also described in Italian Pat. No. 950,545 and in U.S. Pat. Nos. 2,867,185; 3,061,118; 3,091,347 3,404,789; 3,728,597; 4,056,198; 4,065,001; and 4,299,533.
There are several advantages to such systems in addition to the high production rates which can be achieved. For example, such systems are much safer to operate since it is not necessary for an operator to regularly place his hands in the forming press as is the case with manually fed machines. An apparatus of the general type is also advantageous from the standpoint of uniformity in the products made since reliable handling equipment will locate work pieces in precisely the same position for each forming operation.
Problems do arise where such equipment must handle work pieces having irregular dimensions and/or where the press tool is such that rather precise location of a work piece is required in order to achieve a proper forming operation. It has been found that complex and expensive mechanisms must be employed for transporting work pieces to and from forming presses in such cases. The complexity and expense is particularly problematical where the work piece transporting apparatus must carry a work piece laterally into position relative to a press tool, and must then descend with a substantially vertical component of movement to insure accurate positioning of the work piece relative to the tool prior to forming.